Fluid Bearing Device

Abstract

Disclosed is a fluid bearing device in which a high adhesive strength is ensured in fixing another member by adhesion to a resin housing. A bearing sleeve is secured in position inside the resin housing, and a shaft member is radially supported in a non-contact fashion by a dynamic pressure action of lubricant generated in a radial bearing clearance between the shaft member and the bearing sleeve. A metal bracket for mounting the stator coil of a motor is fixed by adhesion to the outer periphery of the housing, in which the adhesion portion of the outer periphery of the housing to be fixed to the bracket is roughened, setting the surface roughness to 0.5 μmRa to 2.0 μmRa.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a fluid bearing device. This fluid bearing device is suitable for use as a bearing device in the spindle motor of an information apparatus, for example, a magnetic disc apparatus, such as an HDD or an FDD, an optical disc apparatus, such as a CD-ROM, a CD-R / RW, or a DVD-ROM / RAM, or a magneto-optical disc apparatus, such as an MD or an MO, the polygon scanner motor of a laser beam printer (LBP), a color wheel for a projector, or the small motor of an electric apparatus, such as an axial flow fan. [0003] 2. Related Background Art [0004] Apart from high rotational accuracy, an improvement in speed, a reduction in cost, a reduction in noise, etc. are required of the motors as mentioned above. One of the factors determining such requisite performances is the bearing supporting the spindle of the motor. Recently, as such a kind of bearing, use of a dynamic pressure bearing superior in the ...

AI Technical Summary

Benefits of technology

[0009] In view of this, it is an object of the present invention to achieve an enhancement in the adhesive strength for the connection between a resin housing and another member, such as a motor bracket.

[0011] Usually, a resin product is formed by injection molding. The molding surface of the mold for injection molding is mirror-finished, so that the surface roughness of the resin product obtained is approximately 0.1 μmRa, which is markedly lower than that of a metal product. By intentionally roughening the surface of the adhesion portion of a resin product thus obtained by injection molding to 0.5 μmRa or more, when connecting the housing and the other member by adhesion, adhesive enters the voids defined by the surface protrusions and recesses resulting from the surface roughening to thereby provide an anchoring effect, so that it is possible to ensure a high adhesion strength. This helps to ensure a high anti-impact property between the resin housing and the member to be connected therewith, so that it is possible to form the housing of resin and to provide a fluid bearing device superior in durability and reliability. Apart from the adhesion portion of the housing (the portion of the housing to be connected to some other member by adhesion), such surface roughening can also be effected on the adhesion portion of the other member (the portion of the other member to be connected to the housing by adhesion) when the other member is formed of resin.

[0018] Since it uses a resin housing, a motor having a dynamic pressure bearing device as described above, a stator coil, and a rotor magnet is inexpensive. Further, since a sufficient level of adhesive strength is ensured, the motor exhibits high impact resistance and is superior in durability and reliability.

[0019] According to the present invention, it is possible to ensure a strong adhesive force for the connection by adhesion between the resin housing and the other member, making it possible to improve the fluid bearing device in terms of durability and reliability.

Problems solved by technology

On the other hand, when the adhesion portion is roughened to an excessive degree, a deterioration in the releasability of the molded product results at the time of molding.

Images